Underfloor assembly and cable distribution system therefor

ABSTRACT

The underfloor assembly for a building comprises corrugated metal flooring units preferably side-by-side with cable distribution ducts, over which is mounted cable trenches. Each distribution duct has a bottom plate and a plurality of inverted U-shaped members with less than all of the members having portions cut away to thus leave the members open under the trenches. The bottoms of the trenches are open where they intersect the ducts, thereby providing easy access between the trenches and the ducts and additional space below the trench to accommodate splices and bends in the cables.

The present invention relates to an underfloor assembly for a metal deckand concrete floor. In particular, the present invention comprises acorrugated metal flooring and a cable distribution system, which arethen covered with an overlying layer of concrete to provide the floor ofa building.

A variety of underfloor cable distribution systems has been proposed inthe art. For example, see Fork, U.S. Pat. No. 3,721,051 and the priorart referred to and cited therein. Other Fork patents describingunderfloor raceways are U.S. Pat. Nos. 3,426,802 and 3,453,791.

The Fork patents describe a variety of electrified deck systemscomprising cellular metal flooring and a series of spaced-apart,electrical cable trenches overlying the cellular flooring. Accessbetween the trenches and the cellular flooring is provided by usingelectrical trenches that have factory-punched openings in the top andbottom of the trench, thereby exposing the cellular flooring underneaththe trenches. Fork U.S. Pat. No. 3,721,051 states that there aredisadvantages to the use of factory-punched openings and providesinstead a so-called "bottomless" trench, wherein the trench has top andside walls, but no bottom. While this may provide advantages over theuse of cable trenches having factory-punched openings, nevertheless thebottomless trench does raise problems relating to economies ofmanufacture, field installation and use by the tenant of the electricalsystem thus created.

The present invention does not use the bottomless trench concept ofFork, but rather the present invention provides an underfloor assemblycomprising, in combination, a cable trench having factory-providedopenings therein overlying corrugated metal flooring units and cabledistribution ducts arranged side-by-side.

In particular, the present invention provides an underfloor assembly fora building, comprising a plurality of elongated, corrugated, metalflooring units and a plurality of elongated, metal cable distributionducts preferably arranged side-by-side with said flooring units, saidflooring units and said cable distribution ducts being adapted to besupported by the structural beams of the building; and a plurality ofspaced-apart elongated cable trenches adapted to carry cables ofdifferent types therein and extending over and transversely across saidflooring units and said cable distribution ducts; said cabledistribution ducts comprising a longitudinally extending support plate,at least two inverted U-shaped members extending longitudinally alongand secured to said support plate for providing at least twolongitudinally extending cell means for containing and separating cablesof different types, all but one of said U-shaped members being omittedat the intersections of said trenches and said cable distribution ducts;said trenches comprising a longitudinally extending U-shaped base panmeans having a bottom portion and opposed side portions, and cover meansfor closing said U-shaped base pan means, said bottom portion of saidbase pan means having apertures therein at said intersections of saidtrenches and said distribution ducts for permitting direct access fromsaid trench to the distribution duct below.

The present invention is illustrated in terms of a preferred embodimentin the accompanying drawings, in which:

FIG. 1 is a diagrammatic top plan view of an underfloor assemblyaccording to the invention;

FIG. 2 is an enlarged top plan view of the intersection of a cabletrench and a cable distribution duct according to the invention, withthe trench covers removed;

FIG. 2A is an elevational view, in section, taken along lines 2A--2A inFIG. 2;

FIG. 3 is a top plan view of the cable trench according to the presentinvention;

FIG. 4A is an elevational view, in section, taken along lines 4A--4A inFIG. 3;

FIG. 4B is an elevational view, in section, taken along lines 4B--4B inFIG. 3;

FIG. 5 is a view similar to FIG. 3 showing the cable distribution ductaccording to the present invention;

FIG. 6A is an elevational view, in section, taken along lines 6A--6A inFIG. 5; and

FIG. 6B is an elevational view in section, taken along lines 6B--6B inFIG. 5.

Referring to the drawings, FIG. 1 shows an underfloor assembly 10comprising conventional corrugated metal flooring units 20 havingalternating crests 21 and troughs 22, joined edge-to-edge in aconventional manner to distribution ducts 30 which are also made ofmetal. The metal flooring 20 and the cable distribution ducts 30 aresupported by structural beams 40, in a conventional manner.

A plurality of cable trenches 50 made of metal rest on the metalflooring 20 and the distribution ducts 30. Trenches 50 are tack-weldedor bolted to the metal flooring 20 and ducts 30 as is conventional.Trenches 50 have removable covers 51 to permit access to thedistribution ducts 30 as will be described in detail hereinafter. Afterthe assembly 10 has been completed, concrete is poured over the metalflooring 20 and cable distribution ducts 30 so as to be level with thetop of the trenches 50, as is conventional. Covers 51 are kept on thetrenches 50 during the pouring of the concrete so as to keep concretefrom entering the trenches 50.

Referring to FIG. 2, it can be seen that the metal flooring 20 and thedistribution ducts 30 are in side-by-side relationship. It is presentlypreferred that ducts 30 be 18 inches wide and be spaced apart four feetcenter-to-center. However, it is within the spirit of this invention tomake the ducts 30 wider than 18 inches and to space them more or lessthan four feet apart. Any conventional corrugated metal flooring may beused as the metal flooring 20. FIG. 2 shows trench 50 with the removablecovers 51 removed for clarity in revealing the intersection of trench 50and distribution duct 30.

As is most clearly seen in FIG. 3, 4A and 4B, cable trench 50 is formedof a U-shaped base pan 52 having a horizontal bottom 52a and uprightvertical sides 52b. Most desirably, the vertical sides 52b are integralwith the bottom 52a of the base pan 52. Covers 51 are removably securedto the top of trench 50 by suitable fastening means (not shown), such asbolts, that are used in cable trenches.

While the vertical walls 52b of base pan 52 are continuous along theextent of trench 50, the bottom 52a of the base pan 52 has severalaccess windows or apertures 52c (FIG. 3) so that when cover 51 isremoved, access to the distribution duct 30 (FIG. 2) is permittedthrough the aperture 52c. Aperture 52c extends longitudinally alongtrench 50 for a sufficient distance such that the edges of the base panbottom 52a will lie approximately at the mid-point of a crest 21 of themetal cellular flooring 20 (FIG. 2A). In this way, there is sometolerance in the placement of trench 50 over the metal flooring units20. Using the preferred spacing and width of ducts 30 set forth above,trenches 50 may be 18 inches wide and apertures 52a may be 30 incheslong.

Preferably centrally located within trench 50 is a U-shaped trough 54which is welded or otherwise secured to the base pan bottom 52a. Trough54 will usually carry electrical power cables 60 (FIG. 2), but in agiven system, any of the cells 56, 57, 58 (FIG. 4A) may be the powercable cell.

As is seen most clearly in FIGS. 3, 4A and 4B, trench 50 is composed ofsub-units 50a, which comprise a pair of opposed side walls 52b, acentrally located base pan bottom 52a, and a section of trough 54coextensive with side walls 52b. Components 52a, 52b and 54 may beseparately formed and then attached together or they may be allintegrally formed, as by roll forming. Sub-units 50a are preferablyshipped with covers 51 attached and they are field assembled to formtrench 50 by bolting adjacent ends of sub-units 50a together. In thisway, each sub-unit 50a has sufficient structural integrity for transportand field assembly.

Each sub unit 50a has half of an aperture 52c at each end, the fullextent of each aperture 52c being formed when adjacent sub-units 50a areconnected.

As best seen in FIGS. 5, 6A and 6B, the distribution duct 30 comprises acorrugated unit providing elongated cells 31, 32 and 33 formed byalternating crests 31a, 32a and 33 and valleys 34. The corrugated unitis secured to an elongated continuous bottom plate 35 by any suitablemeans, such as welding. However, as in the case of trench 50, duct 30may be roll-formed as an integral unit.

At suitable intervals along the length of duct 30, a portion of thecells 31 and 33 is omitted (or cut away) to provide apertures 36, sothat these apertures 36 will provide access to cells 31 and 33 at theareas of intersection between trench 50 and cable distribution duct 30(FIG. 2A). Preferably, the apertures 36 will be pre-formed and not fieldcut. A pre-formed access port 32b may be provided in crest 32a to allowelectrical cable 60 (FIG. 2) lying in member 54 of trench 50 to passfrom the trench 50 through port 32b and thence into cell 32. Mostlikely, port 32b will be field drilled. Cell 32 is the power cell.

FIGS. 2 and 2A illustrate how the cables 60, 61 and 62 enter thedistribution duct 30. Thus, the large apertures 36 in duct 30 permitsfree and easy access of cables 61 and 62 into cells 31 and 33,respectively. It is preferred that the cells 31 and 33 are larger incross-section than cell 32. The larger cells 31 and 33 may be used fortelephone, computer cables and other special services, which as is wellknown, are larger and far more numerous than the electrical power cables60.

While the cross-section of cell 32 remains the same along duct 30, cells31 and 33 have greatly enlarged cross-sectional areas where ducts 30intersect trenches 50. Thus, cells 31 and 33 have a much larger widthunder the trench 50 than inside duct 30 because part of these cells isomitted from duct 30 at the intersections of ducts 30 with trenches 50.As seen most clearly in FIG. 2A, cells 31 and 33 each extend from theinclined side of cell 32 to the opposed inclined wall 22a of theadjacent flooring unit 20.

Given the dimensions above, it is presently preferred that bottom plate35 is 36 inches wide, and that cell 32 has a base that is 3 inches wide.Flooring units 20 are commercially manufactured with crests 21 on 12inch centers, a toe 22b of 1.5 inches and a distance of (measuredhorizontally) of 3 inches from the trailing edge of toe 22b to theleading edge of crest 21. This will provide a width of 9 inches at thebottom of each of cells 31 and 33 and 12 inches at the top, disregardingthe small amount gained from the inclined wall of member 32. This willeasily accommodate large bends in cables 61 and 62, and splices therein,such that the bends and splices will be below (FIG. 2A) the trench 50,thereby enabling the full space inside trench 50 to be used for carryingcables, rather than having to dedicate some of this space for theinevitable bends and splices.

Completing the underfloor assembly 10 are plugs 70 (FIG. 2A), which areinstalled as by welding before the concrete is poured so as to preventconcrete from otherwise entering the open apertures 36 and 52a duringthe cement pour.

The underfloor assembly 10 according to the invention is assembled asfollows. First the metal flooring 20 and the distribution ducts 30 aresecured in place and joined together on beams 40 (FIG. 1) by securingthe toes 22b of a unit 20 to plate 35 (FIGS. 2 and 2A) or to the toes22b of an adjacent unit 30 or 20, respectively, by conventional meansused in constructing corrugated metal flooring, such as by clinchingtogether mating flanges (not shown) on the edges of plate 30 and toe22b. Then the trench sub-units 50a, with covers 51 attached, are setdown, connected together and secured to ducts 30 and to the crests 21 ofthe metal flooring 20. After the concrete is poured and set, covers 51are removed and cables 60,61 and 62 are then fed through the trenches 50and the ducts 30. Interconnections between the cables in trenches 50 andducts 30 are easily made at the desired point of interconnection,because the full extent of the cells 31, 32 and 33 is readily accessed.Bulky splices in the cables 61 and 62 in the trenches 50 and the ducts30 are accommodated below trench 50 in the large cells 31 and 33.Usually, tile or other decorative flooring (not shown) is installed overthe concrete.

Access to the cables 60, 61, 62 in ducts 30 may be effected by the useof vertical accessways (not shown) that are attached to the ducts 30before or after the concrete is poured. However, access to thedistribution ducts 30 may also be easily effected by drilling throughthe concrete to expose duct 30 at the desired location, and thetelephone, computer and electrical cables are all available in onelocation. Accordingly, it can be seen that the tenant need not belimited to a predetermined number and position of access risers orreturns.

In practice, the number and size of cables that provide electrical andother services per unit area of floor, is limited by the number and sizeof trenches 50. Thus, in the present invention, the larger access areaat the intersections of the trenches 50 and ducts 30 enables thetrenches 50 to carry larger size and/or a larger member of cables thanheretofore possible, while maintaining the trenches 50 at a given sizeand number. This is because the larger access area is below the trench50, which in turn enables the splices of cables in trench 50 to thecables in duct 30, and the necessary bends in these cables, to belocated below the trench 50 without using the limited space in thetrench 50 for these purposes.

The bottom 52a of the trench cooperates with the sides 52b, and covers51 to provide trench 50 with sufficient structural integrity to act as abeam. Consequently, the trenches 50 reinforce the concrete and result ina structurally stronger system than if conventional "bottomless"trenches were used.

Further advantages over conventional systems include the fact that theamount of spray fireproofing will be substantially reduced using thepresent invention. Thus, in conventional electrical decks, the entirecellular deck must be spray fireproofed because it is not possible toidentify the cells carrying electrical cables. However, in accordancewith the present invention, the cable distribution ducts 30 are readilydistinguished from the corrugated flooring 20.

Similarly, in conventional electrical decks using a bottomless trench,the entire length of the bottomless trench is heavily sprayed, but inaccordance with the present invention, the trenches 50 need be heavilyspray fireproofed only where they intersect the cable distribution ducts30. It can be seen that this, too, will result in substantial economies,since in the present system there are fewer intersections betweentrenches and ducts than in the bottomless trench system.

Another advantage of the preferred embodiments of the invention is thatthere is approximately the same area of distribution duct available forthe placement of telephone and communication line that exists in thepresent systems. However, all of the area is in one place permittingbigger cables. Furthermore, the area available for high tension cable ismore than sufficient for the technology of today.

What is claimed is:
 1. An underfloor assembly for a building comprisinga plurality of elongated, corrugated, metal flooring units and aplurality of elongated, metal, cable distribution ducts arrangedside-by-side with said flooring units, said flooring units and saidcable distribution ducts being adapted to be supported by the structuralbeams of the building; and a plurality of spaced-apart elongated cabletrenches adapted to carry cables of different types therein andextending over and transversely across said flooring units and saidcable distribution ducts; said cable distribution ducts comprising anelongated, longitudinally extending bottom plate, and at least twoelongated inverted U-shaped members secured to and longitudinallyextending along said bottom plate and defining therewith at least twolongitudinally extending closed cell means having top, opposed side andbottom portions for containing and separating cables of different types,one of said inverted U-shaped members being interrupted at intersectionsof said trenches and said cable distribution ducts such that the top andside portions of a said closed cell are omitted where said closed cellruns under said trench; said trenches comprising an open, longitudinallyextending, U-shaped base pan means having a bottom portion and opposedside portions, and cover means removably secured to and closing saidopen U-shaped base pan means, said bottom portion of said base pan meanshaving apertures therein at said intersections of said trenches and saiddistribution ducts for permitting direct access from said trench to thedistribution duct below.
 2. The underfloor assembly according to claim1, wherein said trenches comprise longitudinally extending cablecompartments therein for containing and separating cables of differenttypes.
 3. The underfloor assembly according to claim 1, wherein saidcable distribution duct comprises a central inverted U-shaped member andan outer inverted U-shaped member on either side thereof to provide acentral closed cell and two outer closed cells, both of said outerinverted U-shaped members being interrupted at said intersection suchthat the top and side portions of said outer closed cells are omittedwhere said outer closed cells run under said trench.
 4. The underfloorassembly according to claim 3, wherein said closed central cell of saiddistribution duct has an opening at the top thereof; said trenchescomprise a longitudinally extending central cable compartment and outercable compartments on either side of said central compartment forcontaining and separating cables of different types; whereby cables insaid outer cable compartments have direct access to said outer closedcells of said distribution duct and cables in said central cablecompartment have access to said closed central cell of said distributionduct via said opening therein.
 5. A cable distribution duct for use inan underfloor assembly for a building, which comprises an elongated,longitudinally extending bottom plate, a plurality of spaced apart,longitudinally extending, inverted U-shaped members secured to andlongitudinally extending along said bottom plate and defining therewitha plurality of longitudinally extending closed cell means having top,opposed sides and bottom portions for containing and separating cablesof different types, at least one of said inverted U-shaped members beingcontinuous and at least one of said inverted U-shaped members beinginterrupted at spaced locations along its length such that the top andside portions of a said closed cell are omitted at said spacedlocations.
 6. The cable distribution duct according to claim 5, whereinsaid inverted U-shaped members comprise a continuous central member andouter interrupted members to provide a central closed cell and outerclosed cells on either side of said central cell, said outer closedcells being interrupted at spaced locations along their length such thatthe top and side portions of said outer closed cells are omitted at saidspaced locations.